This invention relates to a testing apparatus for testing the electrical characteristics of oil-impregnated or gas filled insulating materials.
Conventional oil-impreginated or gas filled insulating materials in sheet form have heretofore been subjected to electrical characteristic testing by the following method. Insulating materials are laid on a lower electrode connected to the low voltage side of a power supply and an upper electrode connected to the high voltage side of the power supply is put on the top surface of the insulating materials. The insulating material and both electrodes are disposed in oil exposed to the atmosphere.
A conventional testing apparatus of this class is disadvantageous in that the characteristics of the oil change when it is exposed to the air, thereby influencing the test data. Since the longer the oil is exposed to air, the greater is the likelihood it will undergo changes in its characteristics, tests carried out over hours are more likely to be adversely affected.
More specifically, the oil bath in the prior art is open to the air and therefore cannot be subjected to testing under oil pressure. Since in the prior art only a single sample is tested at a time, and samples must be replaced after each test, the sample is exposed to harmful air when it is exchanged with a new one, and that confusion occurs among exchanged samples.